Wide inlet rotary pump for circulating liquids under vacuum



28, 1950 E. s. PERRY 2,499,158 WIDE INLET ROTARY PUMP FOR CIRCULTING LIQUIDS UNDER VACUUM Filed 001.. 14, 1946 Emo/vp PERRY i IN V EN TOR.

ATTORNEY.'

Pntented Feb. 28, 1950 WIDE INLET ROTARY PUMP FOR CIRCULAT- lNG LIQUIDS UNDER VACUUM Edmond S. Perry,

mesne assilnments. pany, Rochester, Jersey Rochester, N. Y., ass

llnor, by Eastman Kodak Coina corporation oi' New Application october 14. 194s, serial No. 703,208

3 Claims.

This invention relates to an improved device ier circulating liquids in evacuated apparatus.

The practice of circulating liquids in evacuatedv apparatus by means of conventional pumps is limited by vapor locking of the conduits leading to the inlet ports of the pump. These conduits are usually pipe or tube of `small diameter. Gravitational ow of liquid through them is impeded by liberated gases which, because of their continual expansion, become lodged in the conduits.

This invention has for its object to provide an improved pump for circulating liquids under vacuum such as in a high-vacuum unobstructedpath still. Another object is to provide a pump not subject to vapor lock. A still further object le to provide a wide inlet rotary pump the opera.- tion oi which will not be impeded by the formation of bubbles. Another object is to improve the state of the art. Other objects will appear herematter.

These and other objects are accomplished by my invention which includes a rotary type pump with a wide inlet effected by eliminating the inlet pipe and restricting the size of the head plate to expose the gears at the pump inlet. A pump of this design located, for example, at the bottom oi a liquid drain reservoir in a high-vacuum unobstructed-path still may be used to circulate the liquid to another part of the still.

In the following description wherein like numbers refer to like parts I have set forth several of the preferred embodiments of my invention but it is to be understood that these are given by way oi illustration and not in limitation thereof. In the accompanying drawings wherein I have illustrated two embodiments of my invention, Figure l is a side-by-side rotary gear pump with the head plate removed, Figure 2 is a gear-withingear rotary pump with the head plate removed. and Figure 3 is a 90 rotated section showing the pump attached to a reservoir containing liquid to be pumped. Figure 3 illustrates the operation of the gear-within-gear rotary pump of Figure 2.

Referring to the drawings, numeral lil designates the inlet of the pump. This is similar to a conventional pump except that the inlet conduit has been eliminated and a portion oi the pump housing cut away so as to expose the gears. Numeral il designates the pump outlet. Numeral li designates an impeller on the side-byside type rotary pump. Numeral i3 designates the rotor gear of the gear-wlthin-gear rotary or and numeral i4 Ydesignate the idler or 2 stator gear. Numeral i5 designates the pump housing. Numeral I6 designates the pump head plate or cover. Numeral Il designates the shaft which rotates the pump. Numeral I 8 designates the pump bearing. Numeral I9 designates the base plate of a liquid reservoir. Numeral 210 designates an opening in the base plate to which the pump is connected.

In operation a pump of the type described is placed below the surface of any liquid which it is desired to circulate in the vacuum chamber. The pump inlet I0 is comparatively wide and includes a portion of the gears. Any gas bubbles which form around the inlet can easily rise to the surface of the liquid and escape. By omitting the inlet conduit and cutting away a portion of head plate it around the inlet I have eliminated all possibility of vapor lock and produced a pump which is positive operating. The exhaust portion of the gears is covered by the plate, thus forcing the circulating liquid il. a reservoir so that opening it in this plate coincides with that in head plate it. The gears are then in direct contact with the bulk of the liquid.

The inlet may be as large as possible provided there is no interference with the action of the outlet port. It is only necessary to maintain some bearing surface between the inlet port and outlet port to insure pumping action. Dotted lines have been inserted in Figures 1 and 2 to illustrate the bearing surface required. If the head plate covers the entire gear area except the crescent-shaped portion indicated by the dotted line around inlet port l il there will still be a suiiicient inlet area to prevent vapor locking. 0n the other hand ii' the head plate covers only the crescent-shaped portion of the gear area indicated by the dotted line around outlet port il there will still be sumcient bearing area to allow the pump to function, and the possibility of vapor locking is reduced to a minimum.' The exposed gear area may be restricted to the small area indicated by the dotted line crescent around inlet port it or it may be large enough to include all the gear area except that covered by the dotted line crescent around outlet port i i.

It is obvious that many variations may be made in the size of the inlet opening. The size required depends upon the type of fluid being handled, the degree of vacuum, and the temperature. More volatile uids, higher vacuums, and higher temperatures all go to increase the size of the opening required. Inlet size can be designed to nt operating requirements. For relatively non-volatile liquids. leaving about 15% of the head plate area open around the pump lmet will give a pump having satisfactory perlomance characteristics. For more volatile liquids as much as 75% oi the head plate area may be leit open. I! 25% of head plate area in the vicinity of the outlet is covered there will be suiiicient bearing surface to enable the pump to operate.

What I claim is:

1. In a system i'or handling liquid material under high vacuum conditions, the combination with an evacuable chamber adapted to contain liquid material, of a gear pump assembly com-v prising intermeshing rotatable gear means, a housing enclosing one lateral lace and the peripheral extent of said gear means, an outlet port in said housing adjacent the periphery oi said gear means, and head plate means enclosing not less than 25% and not more than 85% oi' the other lateral face opposite to said one lateral tace of said gear means in a zone adjacent said outlet port, said chamber being arranged to cause liquid material to flow by gravity from said chamber to said pump assembly and having an outlet opening in a lower portion of said chamber of cross-sectional areea not less than area oi' the unclosed portion oi' said other lateral face of said gear means, and generally unconstricted means providing direct communication between said outlet opening of said chamber and said unenclosed portion of said other lateral face of said gear means, said generally unconstricted means having a cross-sectional area not substantially smaller than said outlet opening in said chamber.

2. In a system for handling liquid material under high vacuum conditions, the combination with an evacuable chamber adapted to contain liquid material, of a gear pump assembly comprising intermeshing rotatable gear means, a housing enclosing one lateral face and the peripheral extent of said gear means, an outlet port in said housing adjacent the periphery of said gear means, and head plate means enclosing not less than 25% and not more than 85% of the other lateral face opposite to said one lateral face of said gear means in a zone adjacent said outlet port, said chamber having an outlet opening in a lower portion thereof of 4 with said unenclosed portion ot said other lateral face providing direct communication between said chamber and said gear m 3. In a system for handling liquid material under high vacuum conditions, the combination with an evacuable chamber adapted to contain liquid material, of a gear pump assembly positioned immediately below said chamber and comprising generally horizontally disposed intermeshing rotatable gear means, a housing enclosing the lower lateral lace and the peripheral extent of said gear means, an outlet port in said housing adjacent the periphery of said gear means, a head plate enclosing not less than 25% and not more than 85% of the upper lateral face of said gear means in a zone adjacent said outlet port, said chamber having an outlet opening substantially the same cross-sectional area as the unenclosed portion of said other lateral face of said gear means, said housing being secured to said chamber in liquid-tight relation with said outlet opening in said chamber coinciding in the bottom thereof oi cross-sectional area substantially equal to the area of the unenclosed portion of said upper lateral face, said housing being secured to said chamber in liquid-tight relation with said outlet opening in said chamber directly above and generally coinciding with said unenclosed portion oi said lateral face and thereby providing direct communication between said chamber and said pump assembly.

EDMOND REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS S. PERRY.

Number Name Date 345,969 Harrold July 20, 1886 788,848 Riegel May 2, 1905 834,384 Johnston Oct. 30, 1906 1,035,468 Reagan Aug. 13, 1912 1,442,787 Scheminger, Jr. Jan. 16, 192,3 1,603,395 Mohl Oct. 19, 1926 1,890,152 Hills Dec. 6, 1932 1,900,735 Pomeroy Mar. 7, 1933 2,105,259 Oshei Jan. 11, 1938 2,146,395 Horton Feb. 7, 1939 2,147,777 Oshei Feb. 21, 1939 2,240,056 Schmitz Apr. 29, 1941 2,291.354 Sibley July 28, 1942 2,386,896 Hill et al. Oct. 16, 1945 2,416,987 Fleischer Mar. 4, 1947 2,434,135 Wichger Jan. 6, 1948 FOREIGN PATENTS Number Country Date 2,590 Great Britain June 25. 1880 7,541 Australia May 30, 1927 Certificate of Correction Patent N o. 2,499,158 February 28, 1950 EDMOND S. PERRY It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 55, for the Word designate read designates; column 3, line 27, for "areee read area; hne 28, Jfor than area read than the area; same Ime, for unclosed reed unenclosed;

and that the seid Letters Patent should be reed with these corrections therein thet the same may conform to the record of the case in the Patent Ofoe.

Signed and sealed this 20th day of June, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Oommssioner of Patents. 

